To provide a compact damper pulley having high versatility in which resonance of a rotational shaft is avoided and there is no rotational fluctuation at an engine start from when the engine is started until the rotational shaft reaches an idling speed, and an auxiliary machine driving device equipped with the damper pulley.

The damper pulley 20 includes a hub 21 fixed to a crankshaft 3, a damper mass 22 disposed to surround the outer periphery of the hub 21, and a damper mass elastic body 23 for elastically connecting the hub 21 to the damper mass 22. The hub 21 has a cylindrical boss part 21b projecting in the axial direction. The damper pulley 20 further includes a pulley 25 disposed to surround the outer periphery of the boss part 21b and around which a driving belt 15 is wrapped, and a centrifugal clutch 24 configured to connect the hub 21 to the pulley 25 when the rotational speed (rpm) of the hub 21 is a reference rotational speed (rpm) or higher and disconnecting the hub 21 from the pulley 25 when the rotational speed of the hub 21 is less than the reference rotational speed.